Federal Reserve Chair Janet Yellen is signaling that the central bank could begin raising short-term rates six months after it halts its bond purchases around year’s end.

That was the clearest indication to date of when the Fed might raise its benchmark short-term rate, which has been at a record low near zero since 2008. The Fed has previously resisted specifying the timing of a possible increase in the short-term rate. Its latest statement says the rate could stay at a record low “for a considerable time” after the bond purchases end.

Yellen sought to explain that term at a news conference Wednesday.

“This is the kind of term it’s hard to define,” she said. “Probably means something on the order of six months, or that type of thing.”